Collapsible coaxial flex duct

ABSTRACT

A heating, ventilation, and air conditioning (HVAC) system for a structure having at least one area to be conditioned includes a blower configured to force an airflow through the HVAC system and a duct assembly in airflow communication with the blower. The duct assembly includes a first duct defining a flow path for a first fluid having a first temperature and a second duct having a hollow interior defining a flow path for a second fluid having a second temperature different from the first temperature. The first duct is arranged within the hollow interior of the second duct such that heat is transferred between the first fluid and the second fluid. At least one of the first duct and the second duct is formed from a collapsible material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.63/306,357, filed Feb. 3, 2022, the contents of which are incorporatedby reference herein in their entirety.

BACKGROUND

Embodiments of the present disclosure relate to a heating, ventilation,and air conditioning (HVAC) system, and more particularly, to system forbalancing an air intake and exhaust of an HVAC system.

HVAC systems are used to provide heating, cooling and/or ventilation tobuildings. As buildings become more insulated due to energy efficiencydemands, introduction of fresh, outdoor air into the HVAC system isrequired. Existing systems typically have a single air inlet duct and asingle air outlet or exhaust duct located remotely from the inlet duct.Such a system is not balanced and is not energy efficient. Energyrecovery ventilators, which can be used to balance a system and exhaustare not typically installed due to high cost. There is therefore a needfor a low cost solution to improve the balance and energy efficiency ofHVAC systems.

BRIEF DESCRIPTION

According to an embodiment, a heating, ventilation, and air conditioning(HVAC) system for a structure having at least one area to be conditionedincludes a blower configured to force an airflow through the HVAC systemand a duct assembly in airflow communication with the blower. The ductassembly includes a first duct defining a flow path for a first fluidhaving a first temperature and a second duct having a hollow interiordefining a flow path for a second fluid having a second temperaturedifferent from the first temperature. The first duct is arranged withinthe hollow interior of the second duct such that heat is transferredbetween the first fluid and the second fluid. At least one of the firstduct and the second duct is formed from a collapsible material.

In addition to one or more of the features described herein, or as analternative, in further embodiments the first duct and the second ductare arranged concentrically.

In addition to one or more of the features described herein, or as analternative, in further embodiments comprising at least one mountingbracket arranged within the hollow interior to mount the first ductwithin the second duct.

In addition to one or more of the features described herein, or as analternative, in further embodiments the at least one mounting bracket isformed from a spring steel.

In addition to one or more of the features described herein, or as analternative, in further embodiments the at least one mounting bracket isconfigured to allow a flow of air therethrough.

In addition to one or more of the features described herein, or as analternative, in further embodiments the at least one mounting brackethas a spiral-like configuration extending over an axial length of thefirst duct and the second duct.

In addition to one or more of the features described herein, or as analternative, in further embodiments one of the first fluid and thesecond fluid is outside air and one of the first fluid and the secondfluid is exhaust air.

In addition to one or more of the features described herein, or as analternative, in further embodiments the first duct has a water-permeablemembrane such that water or water vapor is transferrable between thefirst fluid and the second fluid.

In addition to one or more of the features described herein, or as analternative, in further embodiments comprising a drain featureassociated with at least one of the first duct and the second duct.

In addition to one or more of the features described herein, or as analternative, in further embodiments at least one of the first duct andthe second duct has a vertical orientation to drain water or water vaporthat has accumulated therein.

In addition to one or more of the features described herein, or as analternative, in further embodiments at least one of the first duct andthe second duct comprises a plurality of connected duct portions.

In addition to one or more of the features described herein, or as analternative, in further embodiments comprising a coil unit including aheat exchanger, wherein the first duct is coupled to the coil unit andto an inlet opening arranged at an exterior of the structure.

In addition to one or more of the features described herein, or as analternative, in further embodiments the heat exchanger is an evaporator.

In addition to one or more of the features described herein, or as analternative, in further embodiments the coil unit includes a furnace,and the second fluid includes a mixture of air output from the at leastone area to be conditioned and flue gas output from the furnace.

In addition to one or more of the features described herein, or as analternative, in further embodiments comprising a pressure sensor and amovement mechanism arranged within a nested portion of one of the firstduct and the second duct.

In addition to one or more of the features described herein, or as analternative, in further embodiments operation of the movement mechanismis adjustable in response to the pressure sensor to balance a flowwithin the first duct and the second duct.

According to an embodiment, a duct assembly for a heating, ventilation,and air conditioning (HVAC) system, the duct assembly includes a firstduct defining a flow path for a first fluid having a first temperatureand a second duct having a hollow interior defining a flow path for asecond fluid having a second temperature different from the firsttemperature. The first duct is arranged within the hollow interior ofthe second duct such that heat is transferred between the first fluidand the second fluid. At least one of the first duct and the second ductis formed from a collapsible material.

In addition to one or more of the features described herein, or as analternative, in further embodiments the first duct and the second ductare arranged concentrically.

In addition to one or more of the features described herein, or as analternative, in further embodiments comprising at least one mountingbracket arranged within the hollow interior to mount the first ductwithin the second duct.

In addition to one or more of the features described herein, or as analternative, in further embodiments the first duct has a water-permeablemembrane such that water or water vapor is transferrable between thefirst fluid and the second fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 is a schematic diagram of an exemplary heating, ventilation, andair conditioning (HVAC) system according to an embodiment;

FIG. 2 is a perspective view of a nested portion of an inlet duct and anexhaust duct of an HVAC system according to an embodiment;

FIG. 3 is an end view of a nested portion of an inlet duct and anexhaust duct of an HVAC system according to an embodiment; and

FIG. 4 is a schematic diagram of a nested portion of an inlet duct andan exhaust duct of an HVAC system according to an embodiment.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures.

Referring now to FIG. 1 , an exemplary heating, ventilation, and airconditioning (HVAC) system 20 configured to provide a conditioned airflow to at least one area to be conditioned 22 is illustrated. As shown,the HVAC system 20 includes an intake or inlet duct 24 through which afirst fluid, such as fresh, outside air, is provided to the HVAC system20 via an inlet opening 25. The inlet duct 24 may extend through a wall26 of the building or structure containing the one or more areas to beconditioned 22. All or at least a portion of the fresh air from theinlet duct 24 is delivered to a mixing unit 28 via operation of anoutside air damper 30. The mixing unit 28 may alternatively oradditionally be configured to receive a supply or return air RA from onethe one or more areas to be conditioned, such as via return air damper32 coupled to a return air duct 34 extending between the at least onearea to be conditioned 22 mixing unit 28 for example.

The air output from the mixing unit 28 is delivered to one or more coilunits 36. As shown, the coil unit 36 includes a movement mechanism 38,such as a variable speed fan or blower for example. The movementmechanism 38 is configured to move the resulting supply air output fromthe mixing unit 28, which may be fresh air or mixture of fresh air andreturn air, to a heat exchanger 40, such as an evaporator for example,in amounts determined by the speed of the movement mechanism 38.

Although the movement mechanism 38 is shown as being located downstreamfrom the heat exchanger 40, and therefore has a draw-throughconfiguration, it should be understood that embodiments where themovement mechanism 38 is arranged at another located and/or has ablow-through configuration are also within the scope of the disclosure.In the illustrated, non-limiting embodiment, an auxiliary heater 42 isarranged downstream from the heat exchanger 40 and is configured to heatthe supply air. However, it should be understood that in embodimentsincluding an auxiliary heater, the auxiliary heater 42 may be arrangedat another location, such as upstream from one or both of the heatexchanger 40 and the movement mechanism 36 based on the specific designrequirements of the application. Further, the auxiliary heater 42 may belocated remotely from the coil unit 36.

Downstream from the coil unit 36, a supply duct 44 extends to andfluidly connects with the one or more areas to be conditioned 22 by theHVAC system 20. From the area to be conditioned 22, a flow of return airRA is provided to the return air duct 34. A portion of the return air RAmay, but need not be recirculated to the mixing unit 28 via operation ofthe return air damper 32 as previously described. The remainder of thereturn air, also referred to herein as exhaust air EA may be provided toa heat exchanger 46, such as a condenser, before being exhausted to theambient atmosphere exterior of the structure via the wall 26. In anembodiment, an exhaust movement mechanism 48 is configured to move theflow of the exhaust air EA across the condenser 46 and through theexhaust duct 50 extending from the condenser to the air outlet 52.

It should be understood that the ducts illustrated and described hereinmay be formed from a single ducts, or alternatively, form a plurality ofduct portions having any suitable configuration connected together.Additionally, it should be understood that the HVAC system 20illustrated and described herein is intended as an example only, andthat an HVAC system 20 having another configuration is also within thescope of the disclosure. For example, in embodiments where the coil unit36 includes a furnace, a portion of the outside air OA provided to theHVAC system 20 via the inlet duct 24 may be diverted to the burners ofthe furnace. Alternatively, or in addition, in embodiments the exhaustair EA within the exhaust duct 50 may include the flue gas output fromthe heat exchanger of the furnace.

In the illustrated, non-limiting embodiment, at least a portion of theinlet duct 24 is nested with the exhaust duct 50 is nested. Although thediameter of the inlet duct 24 is illustrated as being smaller indiameter than the exhaust duct 50, and therefore the inlet duct 24 isarranged within the hollow interior of the exhaust duct 50 50, in otherembodiments, the exhaust duct 50 may be arranged within the interior ofthe inlet duct 24. As shown, the inlet duct 24 and the exhaust duct 50are mounted concentrically about a longitudinal axis; however,embodiments where the ducts 24, 50 are skewed relative to one another orarranged in another suitable configuration are also contemplated herein.

With reference now to FIGS. 2 and 3 , an example of a first duct 60nested within the interior 62 of a second duct 64, representative of theinlet duct and outlet duct is shown in FIG. 2 . It should be understoodthat the first duct 60 and the second duct 62, in combination, may bereferred to herein as a duct assembly. An interior 65 of the first duct60 defines a flow path for a first fluid, and the interior of the secondduct 64 defines a flow path for a second fluid. The ends of the firstand second duct 60, 64 may be configured to couple via hose clamps oranother connector to standard fittings designed to mount to a wall orduct. In another embodiment, an end fitting is pre-attached to one ofthe ducts 60, 64 prior to installation within the HVAC system 20.Alternatively, an end fitting for both the first and second ducts couldbe pre-attached to one another to facilitate installation into the HVACsystem 20. The end fitting for the first duct may be configured torotate relative to the end fitting for the second duct or vice versa tolock the end fitting into position.

The first duct 60 is mounted within the interior 62 of the second duct64 via one or more mounting brackets 66. A mounting bracket 66 that iscapable of maintaining the relative position of the ducts 60, 64 withoutimpeding the flow in the second duct 64 is contemplated herein. Anexample of a mounting bracket 66 is best shown in FIG. 3 . As shown, themounting bracket 66 may be generally star shaped, thereby defining aplurality of points of contact with both the interior surface of thesecond duct 64 and the exterior surface of the first duct 60. The starshaped bracket 66 may be arranged within a plane, or alternatively, maywrap in a spiral-like configuration extending over an axial length ofall or at least a portion of the first and second ducts 60, 64. The atleast one mounting bracket 66 may be formed from any material, includinga spring steel wire, and a resilient plastic for example.

At least one of the first duct 60 and the second duct 64 is formed froma flexible or collapsible material, such as a coiled hose. In anembodiment, both the first duct 60 and the second duct 64 are formedform a collapsible material.

The nested portions of the first and second ducts 60, 64 are configuredto function like a heat exchanger to transfer thermal energy between thefresh, outside air OA and the exhaust air EA. For example, as theexhaust air EA passes through the portion of the exhaust duct 50 nestedwith a portion of the inlet duct 24, heat is transferred from theexhaust air EA to the fresh outside air OA.

In the illustrated, non-limiting embodiment, the first duct 60,regardless of whether it functions as the inlet duct 24 or the exhaustduct 50, includes a moisture or water-permeable membrane that allowshumidity, such as in the form of water or water vapor for example, to betransferred between the fresh outside air OA and the exhaust air EA. Thewater-permeable membrane may be formed from a suitable polymericmaterial, such as an ionomer known as Nafion®, which is a sulfonatedtetrafluoroethylene based fluoropolymer-copolymer. Features of Nafion®include high temperature-endurance (up to 190° C.), chemical resistance,and water permeability based on temperature and pressure. In anembodiment, the entire length of the first duct 60 is made of thewater-permeable material for simplicity of design and manufacturing. Inother embodiments, only a portion of the first duct 60, such as theportion that is nested within the second duct 64 for example, is made ofthe water-permeable material. Furthermore, embodiments where neither thefirst duct 60 nor the second duct 64 includes a water-permeable membraneare also contemplated herein.

In embodiments where one of the first duct 60 and the second duct 64includes a water-permeable membrane, the duct configured to receive themoisture or condensation therein may be configured such that thecondensation is drained therefrom. In an embodiment, the duct may haveone or more have one or more drain features formed therein to draincondensation collected within the duct. Alternatively, or in addition,the overlapping ducts 60, 64 may have a vertical orientation such thatany water accumulated within either duct is configured to fall viagravity to the lowermost end thereof.

With reference now to FIG. 4 , in an embodiment, a control systemincluding a controller C may be operable to balance the flows betweenthe inlet duct 24 and the exhaust duct 50. Flow balancing may beaccomplished using any suitable flow sensing method. Examples ofsuitable flow sensing methods include, but are not limited to the use ofresistance temperature detector (RTD) flow sensors, pressure sensors,blower or motor torque, and blower or motor rotational speed.

In the illustrated, non-limiting embodiment, the control system includesat least one pressure sensor S for sensing the flow and at least onemovement mechanism or blower 68. Although the pressure sensor S andmovement mechanism 68 are shown as being mounted within the inlet duct24, embodiments where they are alternatively or additionally arrangedwithin the exhaust duct 50 or within another suitable portion of thesystem are also contemplated herein. The pressure sensor S is configuredto monitor a pressure within the duct, and operation of the movementmechanism 68 may be controlled in response to the pressure measured bythe pressure sensor S. For example, the controller C is configured toadjust the speed of the movement mechanism 68 such that the pressurebeing measured is substantially equal to the pressure within the otherof the inlet duct 24 and exhaust duct 50. Balancing the pressure withinthe inlet duct 24 and the exhaust duct 50 will ensure that the flow ofoutside air OA into the system 20 is substantially equal to the flow ofexhaust air EA exhausted from the system 20.

The nested portion of the inlet duct 24 and the exhaust duct 50 asdescribed herein is quick and easy to install and provides a low-costbalanced HVAC system. Further, because the nested portions of the inletduct 24 and the exhaust duct 50 are collapsible, the space required tostore these components on a warehouse shelf or in a work truck islimited.

The term “about” is intended to include the degree of error associatedwith measurement of the particular quantity based upon the equipmentavailable at the time of filing the application.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,element components, and/or groups thereof.

While the present disclosure has been described with reference to anexemplary embodiment or embodiments, it will be understood by thoseskilled in the art that various changes may be made and equivalents maybe substituted for elements thereof without departing from the scope ofthe present disclosure. In addition, many modifications may be made toadapt a particular situation or material to the teachings of the presentdisclosure without departing from the essential scope thereof.Therefore, it is intended that the present disclosure not be limited tothe particular embodiment disclosed as the best mode contemplated forcarrying out this present disclosure, but that the present disclosurewill include all embodiments falling within the scope of the claims.

What is claimed is:
 1. A heating, ventilation, and air conditioning(HVAC) system for a structure having at least one area to be conditionedcomprising: a blower configured to force an airflow through the HVACsystem; and a duct assembly in airflow communication with the blower,the duct assembly comprising: a first duct defining a flow path for afirst fluid having a first temperature; and a second duct having ahollow interior defining a flow path for a second fluid having a secondtemperature different from the first temperature, the first duct beingarranged within the hollow interior of the second duct such that heat istransferred between the first fluid and the second fluid; wherein atleast one of the first duct and the second duct is formed from acollapsible material.
 2. The HVAC system of claim 1, wherein the firstduct and the second duct are arranged concentrically.
 3. The HVAC systemof claim 1, further comprising at least one mounting bracket arrangedwithin the hollow interior to mount the first duct within the secondduct.
 4. The HVAC system of claim 3, wherein the at least one mountingbracket is formed from a spring steel.
 5. The HVAC system of claim 3,wherein the at least one mounting bracket is configured to allow a flowof air therethrough.
 6. The HVAC system of claim 3, wherein the at leastone mounting bracket has a spiral-like configuration extending over anaxial length of the first duct and the second duct.
 7. The HVAC systemof claim 3, wherein one of the first fluid and the second fluid isoutside air and one of the first fluid and the second fluid is exhaustair.
 8. The HVAC system of claim 1, wherein the first duct has awater-permeable membrane such that water or water vapor is transferrablebetween the first fluid and the second fluid.
 9. The HVAC system ofclaim 8, further comprising a drain feature associated with at least oneof the first duct and the second duct.
 10. The HVAC system of claim 8,wherein at least one of the first duct and the second duct has avertical orientation to drain water or water vapor that has accumulatedtherein.
 11. The HVAC system of claim 1, wherein at least one of thefirst duct and the second duct comprises a plurality of connected ductportions.
 12. The HVAC system of claim 1, further comprising a coil unitincluding a heat exchanger, wherein the first duct is coupled to thecoil unit and to an inlet opening arranged at an exterior of thestructure.
 13. The HVAC system of claim 12, wherein the heat exchangeris an evaporator.
 14. The HVAC system of claim 12, wherein the coil unitincludes a furnace, and the second fluid includes a mixture of airoutput from the at least one area to be conditioned and flue gas outputfrom the furnace.
 15. The HVAC system of claim 1, further comprising apressure sensor and a movement mechanism arranged within a nestedportion of one of the first duct and the second duct.
 16. The HVACsystem of claim 15, wherein operation of the movement mechanism isadjustable in response to the pressure sensor to balance a flow withinthe first duct and the second duct.
 17. A duct assembly for a heating,ventilation, and air conditioning (HVAC) system, the duct assemblycomprising: a first duct defining a flow path for a first fluid having afirst temperature; and a second duct having a hollow interior defining aflow path for a second fluid having a second temperature different fromthe first temperature, the first duct being arranged within the hollowinterior of the second duct such that heat is transferred between thefirst fluid and the second fluid; wherein at least one of the first ductand the second duct is formed from a collapsible material.
 18. The ductassembly of claim 17, wherein the first duct and the second duct arearranged concentrically.
 19. The duct assembly of claim 17, furthercomprising at least one mounting bracket arranged within the hollowinterior to mount the first duct within the second duct.
 20. The ductassembly of claim 17, wherein the first duct has a water-permeablemembrane such that water or water vapor is transferrable between thefirst fluid and the second fluid.